#17 Check if Set-Cookie headers are removed for cacheable content

[toonvd]

@ThijsFeryn I have abused bgfetch from softpurging for this, Is there any other way?

[ThijsFeryn]

@toonvd I simplified the logic a bit by removing the soft purge logic.:

• We don't need cache tags
• We need a valid Cache-Control header with a positive TTL
• We can do an initial client request (that is a cache miss) to check the Set-Cookie header
• We can do a second client request (that is a cache hit) to check the Set-Cookie header
• We can monitor the BerespUnset "Set-Cookie: testcookie=1; path=/; HttpOnly" tag in the logs through logexpect

[ThijsFeryn]

@toonvd I also added a HEAD request test.

Can you run this test again. If it succeeds & you agree with the logic I used, go ahead & merge.